Process of producing phthalimids



Patented Apr. 3, 1923.

UNITED STATES PATENT OFFICE.

HARRY D. GIBBS, OF PENNS GROVE, NEW JERSEY, ASSIGNOR TO E. I. DU I ONTrm NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OFDELAWARE.

No Drawing.

1 To all whom it camera:

. action between napthalene, oxygen, and

Be it known that I HARRY D. GIBBS, a citizen of the United, tates, and aresident of Penns 'Grove, in the county of Salem and Stateof New Jersehave invented a certain new and useful rocess of Producing Phthalimids,of which the following is a specification.

' This invention relates to the production of phthalimids, and comprisesinducing a rea primary amine, or between phthalic anhydride and aprimary amine, while the several reacting substances are in the vaporphase. When phthalimid itself is to be produoed ammonia is used in placeof a primary A amine.

One'object of my invention is to -provide a continuous process for theproduction of phthalimids fr0m naphthalene, air and ammoma or primaryamines.

Other objects of my invention will be apparent from the followingdescription.

I have discovered that good yields of phthalimids are obtainable by thecatalytic oxidation of naphthalene in vapor form in the presence ofvapors of ammonia or primary amines; and that excellent yields ofphthalimids are also obtainable by bringing the vapors of ammonia orprimary amines into contact with the phthalic anhydridecontaining vaporsresulting from the catalytic oxidation of naphthalene.

The condensed equation for these reactions can be written as followswhere R represents a hydro en, alkyl, or aryl radical. The compoun NH Rmay be referred to generically as a substance containing the groiip NHCatalysts WhlCh have found suitable for accelerating the oxidation ofnaphthalene by air, are the oxides, and other compounds, of

metals of the fifth, sixth and eighth groups of the periodic system, andparticularly the oxides of vanadium, molybdenum, nickel, and platinum.The catalyst is preferably deposited on, or caused to impregnate, an

1 raocnss or PRODUCING rHrnA'LImms.

Application filed February 24, 1920, Serial No. 860,828.

" then cooled to condense and separate from the more yolatile productsthe phthalimid or substituted phthalimid which has been formed.

Instead of mixing the. ammonia or primary amine with the gases leavingthe catalyst, the ammonia or primary amlne may be mlxed wish the airorwith the naphthalene vapors, or introduced into the airnaphthalene'vapor mixture, at any time prior to the oxidation of the naphthalene.

In patents 1,284,888 and 1,285,117 it has been shown that phthalicanhydride can be satlsfactorlly produced by passing an airnaphthalenevapor mixture into close contact witha catalyst composed of an oxide ofvanadium. or molybdenum. The equatlon for the r'eactlon may be written 7co 2Q0 a+9Oa==2C H4 O+4C01+4Hg0.

It seems probable that in the formation of phthalimids according to myinvention in which a mixture of primary amine naphthalene vapor, and airare passed over the; cat alylst, the naphthalene is first oxidized tophthalic anhydride, and the latter, perhaps in the nascent state, reactswith the primary amine to form the phthalimid, in accordance with thefollowing equation where R represents a hydrogen, alkyl, or arylradical.

As examples of primary amines which I may use as the source of theimidmitrogen there may be mentioned methylamine ethylamine, yielding thecorresponding alkylphthalimids; and aniline, 0-, m, and ptoluidines,zylidines, phenylenediamines, naphthylamines, amino-acids,amino-phenols,

halogenated primary amines such as chloraniline, etc., yielding thecorresponding arylphthalimi My invention, although preferably carriedout by bringing ammonia or a primary amine into contact with vapors ofphthalic anhydride resulting directly from the catalytic oxidation ofvapors of naphthalene, is not limited to this procedure, but may also becarried out by vaporizing phthalic anhydride produced by any method andmixing these vapors with ammonia or a primary amine. I consider itessential however that the reaction be broughtin the vapor phase, and(preferably at -a temperature above Naphthalene vapor is mixed with airin excess of the amount theoretically required to oxidize thenaphthalene to phthalic anhydride, and the mixture is passed throughfinely powdered oxids of vanadium maintained at a temperature of about500 C. As the products of reaction issue from the reaction chambercontaining the catalyst they are mixed with ammonia at such a rate thatall of the phthalic anhydride which is.

present in the gas mixture will be converted into phthalimid. The gasmixture is then cooled to condense the phthalimid thus formed. The rateat which it is necessary to introduce ammonia may be readily determinedby testing the gas mixture leaving the catalyst for itsphthalicanhydride content, or by testing the final gas mixture, aftercondensing out all the phthalimid, to ascertain the extent to whichammonia/in excess has been used.

11. Methyl-phthalimid.

A current of heated air carrying naphthalene and meth 'lamine both inthe vapor phase and in suc proportion that the gas mixture containssufiicient oxygen to oxidize the naphthalene to phthalic-anhydride andthe methylamine in such uantity necessary to convert the phthalic-anydride formed to methyl phthalimid, is passed into contact with acatalyst as previously described. The naphthalene is oxidized tophthalic-anhydride and so soon as any phthalic-anhydride is formed, itis converted to methyl phthalimid by the methylamine. In this way thephthalic-anh dride is fixed by the union with the met ylamine so soon asit is formed, the process being continuous.

III. Jhtlzalam'l (i. e., phenyZ-phtkalimz'd.)

Naphthalene vapor is mixed with air in excess of the amounttheoretically required to oxidize the naphthalene to phthallc-anhydride,and the mixture is then passed dride or para-toluidine through finelypowdered oxids of vanadium maintained at a temperature of about 500 C.The gases as they pass outof chamber 4 contain among other products ofthe reaction, phthalic-anhydride in the vapor phase and these gases areat this point, mixed with an amount of aniline sufficient to unite withthe phthalic-anhydride. The reaction between the phthalic-anhydride andthe aniline takes place at once in the sense of the equation:

co co and the products of the reaction pass into a condensing chamberwhere the gases are cooled. The solid products of the reaction condenseand may be removed through suitable outlets, while the gases pass on tobe further treated, if desired, for the recovery of by products.

IV. Para-toZyZ-phtka-Zimid.

Phthalic anhydride which has been produced by the catalytic, vaporphase, oxidation of naphthalene, or by any other process,

is vaporized and mixed with the vapors of para-tolui'dine at atemperature above the vaporization point of para-toluidine. products ofthe reaction are carried through a condensing chamber where thepara-tolylphthalimid is condensed and separated from water vapor and anyphthalic anhythat may have failed to react:

The particular amines mentioned in the above examples may be replaced byother primary amines depending upon the particular phthalimid desired.Although a phthalimid is the principal product formed in the aboveexamples, it will be understood that other products may be formed insmaller quantities, dependlng upon the conditions of the reaction.

While I have described my invention above in detail, I wish it to beunderstood that many changes may be made therein without departing fromthe spirit of my invention.

I claim:

1. The process of producing a phthalimid which comprises causing asubstance containing the group NH to react with the prod- The 3. Theprocess of producing a phthalimid which comprises passing a. gaseousmixture consisting of naphthalene, oxygen, and a substance containingthe group NH into contact with a catalytic compound of a metal of one ofthe fifth, sixth and eighth groups of the periodic system, whilemaintaining the catalyst at a temperature between 200 and 650 C.

4. The processof producing a phthalimid which comprises passing agaseousmixture containing naphthalene, oxygen, and a primary amine into contactwith a catalyst capable of accelerating the oxidation of the naphthaleneto phthalic anhydride, while maintaining the catalyst at a temperaturebetween 200 and 650 C.

5. The process of producing a phthalimid which comprises forming amixture, while in the vapor phase, of phthalic anhydride and a primaryamine.

6. The process of producing a phthalimid which comprises forming amixture, at a temperature above 100 0., of vapors of phthalic anhydrideand a substance containing the group N11 7. The process of producing anaryl phthalimid which comprises forming a mixture, at a temperatureabove 100 (3., of vapors of phtha-lic anhydride andof a primaryarylamine.

8. The process of producing phenylphthalimid which comprises forming amixture, at a temperature above 100 (3., of vapors of phthalic anhydrideand of aniline.

9. The process of producing an arylphthalimid which comprises passingover a catalytic oxidizing agent vapors of naphthalene and primaryarylamine mixed with a sufiicient amount of an oxygen-containinganhydride, while maintaining the catalyst at a temperature between 200and 650 C.

10. The process of producing phenylphthalimid which comprises passingover a catalytic oxidizing agent vapors of naphgas to oxidize thenaphthaleneto phthalic thalene and aniline mixed with a sufficientamount of an oxygen-containing gas to oxidize the naphthalene tophthalic anhydride, while maintaining thecatalyt-t at a temperaturebetween 200 and 650 C.

In testimony whereof I affix my signature.

HARRY D. GIBBS.

